Even though he was in the last row of the plane, Anderson said the flight attendants wouldn't let him stick his knees out into the aisle, so he was forced to sit with them jammed into the metal tray table on the seat in front of him.

Anderson said he asked to be moved to an exit row seat, which typically has more legroom.

"The stewardess and I talked before the takeoff," he said. "She asked if anyone in the emergency row would switch spots with me [but] came back and said, 'You're stuck'."

Brooks Anderson stands at 6'7" and is shown here with his grandparents.

When none of the other passengers offered to help, Anderson said he decided to take matters into his own hands and asked if he could stand for the flight.

"I said, 'I need to do something about this, is it O.K. if I stand after the seatbelt sign is turned off?,'" he said. "She said it was O.K."

It got to the point where if the attendent wouldn't let him stand, Anderson said he seriously considered getting off the plane and missing the flight altogether.

"Like Being on a Subway"

"If I had to sit in my seat the whole time, I would have been in physical pain, with metal jamming into my knee caps for the whole flight," Anderson explained.

He then spent the remainder of the flight "dodging people going to and from the bathroom."

"It's like being in a subway car for two-and-a-half hours, which is awful," he said, adding that there was luckily no turbulence during the flight.

"It's bizarre," said Anderson's mother, Katie Anderson. "This was the first time he's been treated like this."

"Spirit Airlines Is out of Their Mind"

The space between economy class seats on a Spirit Airlines Airbus A321 is about 28 inches, which is below the typical 31 inches.

Katie Anderson said it was the first time anyone in their family had flown Spirit Airlines, and that the attendant at the counter who checked in her son said they couldn't accommodate his tall stature. There were no exit row seats available.

"He arrived at O'Hare in plenty of time, and asked for a seat," she said. "He got there, he asked for a bulkhead or exit row. He knows to ask, and usually the airlines are pretty willing."

"They want me to pay money to reserve an exit row in advance," Brooks said. "It's something other people don't have to do at all."

Travel expert John DiScala, aka JohnnyJet, said having someone stand during a flight can be incredibly dangerous because of unexpected turbulence.

"That's the craziest thing I've ever heard," he said. "Spirit Airlines is out of their minds to tell someone to stand during the flight.

"It's got to be a safety hazard sitting in such tight quarters when you're so tall," he added.

DiScala added that Anderson was also at fault for not properly doing his research on Spirit Airlines and their notoriously small seats.

"That would be the last airline I would book if I were 6'7"," DiScala said. "This guy was asking for it. JetBlue would have been better for this."

JetBlue offers 34 to 38 inches of legroom, and those extra inches add up. While JetBlue hosts 150 seats on its jets, Spirit is able to squeeze in 178 seats. The result is cheaper air fare but less legroom.

Andersons Say They're Still Waiting to Hear Back from Spirit Airlines

When asked if he had looked into Spirit's seat size before booking the flight, Anderson said, "that's not something I thought about."

"I always ask for exit rows when I get there, and they didn't have one," he added.

After his ordeal on his flight down to Florida, Anderson's mother said she tried to change her son's flight when he was heading back to Chicago. When she called Spirit, Anderson said she inquired what they could do for her son's height and then their policy for disabled passengers.

"It's first come, first serve," she said she was told.

Kindness From a Fellow Passenger

When it came time to fly back to Chicago, Anderson and his mother went to the counter together to see if the airline would accommodate him. This time, a passenger offered to help.

"There was a guy who was 5-foot, maybe 5'2" at the most, checking in at the same time," Katie Anderson explained. "He turned to my son and said, 'I have a first class ticket and I'll give you my seat.'"

But when Spirit offered him an exit row seat, waiving the extra fee after hearing his story, he gladly took it.

"I didn't want to inconvience that guy," Anderson said. "As long as I found the solution [where] I could sit, that was fine with me."

Anderson said both he and his mother have written several emails to Spirit, but are still waiting to hear back.

"It blows my mind," Katie Anderson said.

Spirit spokesperson Misty Pinson issued a statement to ABC News via email regarding the incident, writing, "We do offer the option of exit row seating and our Big Front Seats for customers who prefer more legroom. We do not require customers to stand during flight."

While Spirit's Big Front Seats do offer at least 36 inches of legroom, each costs an additional fee, starting at $25, and there are only four of them on their jets, according to their website.

The FAA's website said it's not illegal to stand during a flight, but passengers must be seated with their seat belts fastened for takeoff and landing. The agency also strongly recommends passengers remain seated with their seat belts fastened during the entire flight in case of turbulence.

Every year, approximately 58 people in the U.S. are injured by turbulence while not wearing their seat belts during a flight, according to the FAA. From 1980 through 2008, U.S. air carriers had 234 turbulence accidents, resulting in 298 serious injuries and three fatalities.

FAA Says They're Investigating the Incident

FAA spokesperson Les Dorr said they are "aware of the incident and are investigating," but that a investigation like this would take several days.

He added that "the provision in the regulation is that if the seat belt sign is lit, everyone has to have their seatbelt on."

Dorr also acknowledged that fines are "typically against an individual" who fail to wear a seatbelt when required to, but if it was the airline that told the young man to stand, as it seems to be in this case, then the airline is at fault.

Anderson said his next step is to possibly speak with the FAA about what happened to him.

"I think that's something that we need to bring up because...other people out there are as tall as me," he said. "There's gotta be a way to curb the shrinking of seats...and make it reasonable for me to fly."